Classification of refractory clay
Refractory clay is the main raw material for the production of aluminosilicate refractory materials. All kinds of hard clay, soft clay, semi-soft clay and clay shale with a refractoriness requirement higher than 1580℃ are collectively referred to as refractory clay.
Natural refractory clay is usually a mixture composed mainly of kaolinite as the main component of clay minerals, that is, hydrated silicate as the main body, and mixed with free quartz, yellow iron stone, rutile and organic matter, etc. This kind of non-single mineral is mostly a dispersion composed of particles with a diameter of less than 1.2 μ m.
According to the different formation conditions of clay, it can be divided into primary clay and secondary clay. Primary refractory clay refers to the clay formed after the weathering of the parent rock (such as feldspar), which still remains in its original location. Secondary clay, also known as drift-accumulated clay, is clay that is transferred from primary clay to other places under natural dynamic conditions and then redeposited. It has fine particle size, high dispersion and high plasticity.
The refractory clays applied in the refractory materials industry mainly fall into the following two categories.
- Hard clay is characterized by its dense structure, high hardness, extremely fine particles, difficulty in dispersion when exposed to water, and very low plasticity. This type of clay often appears light gray, grayish white or gray in appearance. The shell-like fracture surface, some have a slippery feeling and are prone to weathering and breaking into small pieces.
- Soft and semi-soft clays are often in the form of lumps, with a soft texture and good plasticity. The color of such clays varies greatly due to the different types and contents of impurities. From grey, dark grey to black; There are also those in purple, light red and white.